Rotary hearth furnace



:5. E. -TALLEY June 13, 1933.

ROTARY HEARTH FURNACE Filed Feb. 18, 1931 2 Sheets-Sheet 1 INVENTOR fwdwa. 70241 m. a

June 13, 1933. i R; E TALLEY 1,913,999v

Ronni HEARTH FURNACE Filed Feb. 18 1951 2 Sheets-Sheet 2 Eye.

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INVENTOR fwd J 7 fiyw -ma Fatented June 13, 1Q

.aannar. n. rumfor rmmsrrvma ROTARY HEABTE FURNACE Application fled February 18, 1931. Serial Io. 518,811.

This invention relates to rotary hearth furnaces, more es ially to the hearth and wall structures such furnaces, and it is among the objects of this invention to provide rotary. furnaces in which the hearth shall be free to expand without interferring with the side wall. forming the furnace chamber.

A further object of the invention is to provide a wall structure of especially designed tile which shall prevent displacement of the tile due to expansion of the furnace wall.

-. Heret'ofore, it wascustomary to construct the hearth of a rotary furnace so that its outer periphery was within the limits of the inner dimension of the annular wall structure, clearance being provided to prevent interference of the rotating hearth when the latter expanded due to high temperature of the furnace chamber.

=In this type of furnace, the upper portion of the hearth expands due to high temperature, the blocks of refractory material, of which the hearth is constructed, do not return to their original position because there is no external orce or pressure available to return them to this position. As a consequence of this expansion, cracks appear between the blocks when the hearth is subjected to cooling, and the cracks are filled with dirt and small particles of refractory so that when the hearth is again brought to a high temperature it will expand to a still larger diameter until in the course'of time, the progressive expansion of the hearth is such as to render it inoperative.

vSuch expansion has beenexperienced to be as much as to take up four inches of clearance between the hearth and the inner dimension of the furnace wall, and the present invention is desi ed to overcome the aforementioned difiicu ties.

In accordance with the present invention the rotary hearth is below the side wall, not encompassed by it, and is, therefore, free to expand without interference with the side wall structure. Furthermore, the outer periphery of the hearth is exposed to atmospheric temperature permitting the use of curb angles or other suitable retaining means to hold the hearth refractories in position.

In the accompanying drawings constituting a part hereof and in which like refer 5 once characters designate like parts, Figure 1 is a sectional elevational view of a rotary furnace embodying the principles of this invention; Figure 2 a diagrammatic view illustrating the tile structure of the side wall 69 of the furnace; and Figures 3 and 4, 5 and 6, 7 and 8, and 9 and 10 are side and end elevational views, respectively, of the tile employed in the construction of the side wall.

With reference to Figure 1 of the drawings, the structure therein illustrated comprises a hearth 1 mounted on a casting generally designated at 2, having a gear-tooth rack 3 and a ball race 4 by means of which it is supported on ball bearings 5 which are mounted on a supporting base 6..

v The'hearth'is rotated by a ear drive generally designated at 7, of w ich a beveled gear pinion 8 meshes with teeth 3 of the rame 2, the gear being actuated through suitable reduction gearing 8a, and a motor generally designated at 9.

Above the hearth 1 is a side wall and roof construction, 10 and 11, respectively, -j

which form the furnace chamber 12. The side wall 10 consists of a lurality of tile blocks which are supported y a sheet metal housing or shell 13 having a flange 14 projectin inwardly at the bottom to prevent the ti e blocks from slipping downwardly.

The shell 13 of the side wall is supported on pillars 15 which are ofiset to provide suflicient clearance for a sand seal 16 to revent the escape of heat from the furnace cliamber apdthe ingress of air to the interior there- 0 a The sand seal consists of a structural element 17 of substantially Z shape which is attached to the shell 18 of the hearth to form a channel sha groove which is filled with sand in whic a vertically de ending flange member 19 projects from we 1 10 to form the seal.

The side wall 11 of the furnace may be supporting ledge 14 at the bottom (it the furnace shell 13 is protected from direct radiation of heat in the furnace chamber. Tiles B and C are wedge shape pieces of the same general form as tile A, but cut to the shape necessary to provide flue openings 22, shown by dotted lines-in Figurel. 'llile B rests against the furnace shell 13 and is selfsupporting in the same manner as the tile A. Tile l) is essentially a counterpart of tile A except that it is provided with a recess 23 along the inner edge which is shaped to receive tile C after the manner shown in Figure 2.

The reinforcing angle at the bottom of the tile structure provides a supporting led e for the circular Wall and the dome are which is carried on the circular wall, the tile structure in turn being supported by the'members 15.

From the construction herein described, it is apparent that the tile comprising the furnace wall cannot move downwardly on account of the ledge which supports them; that they cannot move outwardly on account of the retaining steel shell 13 which encircles them; and that they cannot move inwardly on account of their wedge shape, thus rendering the wall entirely self-su orting to permit the hearth to rotate free y eneath the wall as shown.

In Figure l a portion of a material charging and discharging door structure is shown in elevation, and to provide for the support of tile above-the door and not impair the strength of the furnace wall, a heavy metal yoke 25 is provided, this yoke bein referably a single casting or forging with nwardly projecting flange which engages the tile in a manner similar to the ledge 14 of the outer shell 13.

Furnaces of the type described herein have a wide application for the heating of billets, plates, or other small parts prior to forging, rolling or pressing.

Although one embodiment. ofthe invention has been herein illustrated and described, it will be obvious to those skilled 7 my hand.

cessed sides for receiving complementary shaped sides of adjacent tile to form vertical flues having outlets at the bottom of the inner wall, metal sheathing surrounding said tile and constitutin a support for the wall, the bottom of the s eathing extending partially below the tile, apluralityifoi standards mounted insp'aced relation and adapted for mounting the tile supporting sheathing in spaced relation 'w' h the. furnace floor, anda rotary hearth i'spos ed in spaced relation below and extending to the outer limit 6f the furnace wall out of contact therewith.

2. A rotary hearth furnace comprising in combination a circular hearth, side wall and roof structure forming a heating chamber, the'side wall and roof structure being supported above the hearth and the side wall having flues extending vertically therein and communicating at their lower end with the interior of the heating chamber adjacent the upper surface of the circular hearth, and means for rotating said hearth, said hearth having its upper surface ofrefractory material and said upper surface having a diameter greater than the inner diameter of the side wall.

In testimony whereof I have hereunto set Barman 5n. TALLEY.

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